31517610991 has 2 divisors, whose sum is σ = 31517610992. Its totient is φ = 31517610990.

The previous prime is 31517610947. The next prime is 31517611031. The reversal of 31517610991 is 19901671513.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31517610991 - 2¹¹ = 31517608943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31517610391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15758805495 + 15758805496.

It is an arithmetic number, because the mean of its divisors is an integer number (15758805496).

Almost surely, 2^31517610991 is an apocalyptic number.

31517610991 is a deficient number, since it is larger than the sum of its proper divisors (1).

31517610991 is an equidigital number, since it uses as much as digits as its factorization.

31517610991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51030, while the sum is 43.

The spelling of 31517610991 in words is "thirty-one billion, five hundred seventeen million, six hundred ten thousand, nine hundred ninety-one".